If I had a client that I did not make sure that I had a consent form signed for and I had an important function to go to or field trip and no signed form and the parent of that child was unable to leave work in time to get the child before we left ... it's my fault and I'd be stuck having to stay with the child until the child got picked up. I would never leave the house with another person's child without written consent. I would however be peeved (at myself and probably at the parent if I had spoken to the parent previously about having the form signed) but I would not take the child. The next day I'd have the parent sign the consent form or give a termination notice

DItton on what MV said